JwtRequestFilter

package ru.gurzhiy.springsecurityjwt.filters;


import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.web.authentication.WebAuthenticationDetailsSource;
import org.springframework.stereotype.Component;
import org.springframework.web.filter.OncePerRequestFilter;
import ru.gurzhiy.springsecurityjwt.service.MyUserDetailsService;
import ru.gurzhiy.springsecurityjwt.utl.JwtUtil;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/***
 * intercept every request just once and then examine the header
 */
@Component
public class JwtRequestFilter extends OncePerRequestFilter {


     private final MyUserDetailsService myUserDetailsService;
     private final JwtUtil jwtUtil;

    public JwtRequestFilter(MyUserDetailsService myUserDetailsService, JwtUtil jwtUtil) {
        this.myUserDetailsService = myUserDetailsService;
        this.jwtUtil = jwtUtil;
    }

    @Override
    protected void doFilterInternal(HttpServletRequest request,
                                    HttpServletResponse response,
                                    FilterChain filterChain) throws ServletException, IOException {

        String authorizationHeader = request.getHeader("Authorization");
        String username = null;
        String jwt = null;

        if (authorizationHeader != null && authorizationHeader.startsWith("Bearer")){

            jwt = authorizationHeader.substring(7);
            username = jwtUtil.extractUsername(jwt);
        }

        if (username != null && SecurityContextHolder.getContext().getAuthentication() == null) {

            UserDetails userDetails = this.myUserDetailsService.loadUserByUsername(username);
            if (jwtUtil.validateToken(jwt, userDetails)){

                UsernamePasswordAuthenticationToken namePassAuthToken = new UsernamePasswordAuthenticationToken(
                 userDetails, null, userDetails.getAuthorities());
                namePassAuthToken.setDetails(new WebAuthenticationDetailsSource().buildDetails(request));
                SecurityContextHolder.getContext().setAuthentication(namePassAuthToken);
            }

            filterChain.doFilter(request, response);
        }


    }
}